This invention relates to wireless digital communication systems, and in particular to microcellular packet communication systems, and more particularly to microcellular personal communication systems employing packet communication protocols with a backhaul channel for communication with a wire communication infrastructure.
As personal wireless communication systems such as in cellular telephony proliferate, the spectrum available to the wireless user for accessing cell sites for interactive communication becomes premium. There is great pressure to shrink the cell size of cellular telephone systems, for example, in order to promote frequency reuse and ultimately increase user density and capacity, as well as to reduce the required transmitter power for battery-operated portables. This is the trend toward so-called microcellular systems.
A major drawback of conventional microcellular architectures and systems is the cost of the infrastructure. As the number of required cell sites increases, there is a corresponding increase in the requirement for capital outlay for fixed cell site transmitters and receivers as well as increased maintenance overhead for the fixed cell sites. One of the major cost considerations in a communications architecture is the need to provide a backhaul channel. A backhaul channel is a communication link between the cell sites and the trunk resource or the switching fabric of the wire communication system. It has been assumed that the backhaul channel must be a wired connection between the cell site and the wired communication system, including the nearest central office of the public telephone systems. However, the best cell sites are frequently not convenient or even suited for wired channel connection into the wire communication system.
In the past the conventional wisdom has been to model and provide backhaul access and actual backhaul communication of the same bandwidth capacity. One reason for this modeling scheme is that it was not known how best to model or control wireless central switching.
Metricom, the assignee of the present invention, has developed a communication system which is used for access/backhaul, with wired access to thousands of remotely-located nodes and then a wireless infrastructure for relatively high-density communication by means of a purely wireless peer-to-peer packet communication-based network. This systems architecture is distinguishable as an inverse of a wireless microcellular architecture with a wired backhaul channel. What is needed is a communication system which has a backhaul channel provided without the difficulties and expense associated with providing a wired backhaul channel.